Stabilized biodiesel fuel compositions

ABSTRACT

Disclosed are stabilized biodiesel fuel compositions, which compositions comprise a biodiesel fuel, for example the methyl esters of the fatty acids of rapeseed or soy oil, and one or more additives selected from the group consisting of the 3-arylbenzofuranones and the hindered amine light stabilizers, and optionally, one or more hindered phenolic antioxidants.

This application claims benefit under 35 USC 119(e) of U.S. provisional application No. 60/756,090, filed Jan. 4, 2006, the contents of which are hereby incorporated by reference.

The present invention is aimed at biodiesel fuel (or bio-fuel) compositions, stabilized against the deleterious effects of heat, light and oxygen by an effective amount of a stabilizer selected from the group consisting of the 3-arylbenzofuranone stabilizers and the sterically hindered amine light stabilizers, or an effective amount of a stabilizer selected from the group consisting of the 3-arylbenzofuranone stabilizers and the sterically hindered amine light stabilizers in combination with a stabilizer selected from the group consisting of the hindered phenolic antioxidants.

BACKGROUND

WO2004055141 teaches the stabilization of fats, oils and food. The stabilizers are selected from the group consisting of the 3-arylbenzofuranones, long chain N,N-dialkylhydroxylamines, substituted hydroxylamines, nitrones and amine oxides.

U.S. Pat. No. 6,548,580, to Rohde, et al., teaches ethylene homo- and copolymers stabilized by sterically hindered amines or by N-hydroxy or N-oxyl derivatives to produce articles for the storage and transport of biodiesel fuel.

JP2004059720 discloses polyoxymethylene resin containing a hindered amine light stabilizer that is used in a part in direct contact with a bio-diesel fuel.

EP1170296 teaches a process for the preparation for 3-aryl-benzofuranones. Fuel additives are disclosed therein.

EP1486555, EP1484387 and EP1484388 disclose a low corrosive fuel composition for use in a blue flame burner or an optimized yellow flame burner of a boiler.

Biodeisel fuel is of increasing importance as a renewable fuel source. It may for example be employed as a fuel itself, or may be used in combination with diesel fuel.

SUMMARY

Disclosed are biodiesel fuel compositions stabilized against the deleterious effects of heat, light and oxygen, which compositions comprise

a biodiesel fuel and

an effective stabilizing amount of

one or more additives selected from the group consisting of the 3-arylbenzofuranone stabilizers and the hindered amine light stabilizers and

optionally, one or more additives selected from the group consisting of the hindered phenolic antioxidants.

Also disclosed is a process for the stabilization of a biodiesel fuel against the deleterious effects of heat, light and oxygen, which process comprises

incorporating into a biodiesel fuel

an effective stabilizing amount of

one or more additives selected from the group consisting of the 3-arylbenzofuranone stabilizers and the hindered amine light stabilizers and

optionally, one or more additives selected from the group consisting of the hindered phenolic antioxidants.

DETAILED DISCLOSURE

Biodiesel fuels are a renewable resource and are of increasing importance.

Biodiesel fuels typically comprise lower alkyl fatty acid esters, prepared for example by transesterifying triglycerides with lower alcohols, e.g. methanol or ethanol. A typical biodiesel fuel is the fatty acid methyl ester of rapeseed oil or of soy oil. Sources for biodiesel fuel include vegetable and animal sources. Recycled cooking oil may be a source of biodiesel fuel.

Biodiesel fuel and its preparation is taught for example in U.S. Pat. Nos. 5,578,090, 5,713,965, 5,891,203, 6,015,440, 6,174,501 and 6,398,707, the contents of which are hereby incorporated by reference.

Biodiesel fuel of the present invention for example comprises lower alkyl esters of a mixture of saturated and unsaturated straight chain fatty acids of from 12 to 22 carbon atoms, derived from vegetable or oleaginous seeds. The term “lower alkyl ester” means C₁-C₅ esters, in particular methyl and ethyl esters. The mixture of methyl esters of the saturated, monounsaturated and polyunsaturated C₁₆-C₂₂ fatty acids are what is typically known as “biodiesel” or “rapeseed methyl ester”.

Biodiesel fuel according to the present invention is 100% lower alkyl fatty acid ester, or is a combination of a lower alkyl fatty acid ester with diesel fuel. The present biodiesel fuel is for example between about 5 and about 95 weight percent fatty acid ester and between about 95 and about 5 weight percent diesel fuel. For example, the present biodiesel fuel is between about 10 and about 90 weight percent fatty acid ester and between about 90 and about 10 weight percent diesel fuel. For instance, the present biodiesel fuel is between about 25 and about 75 weight percent fatty acid ester and between about 75 and about 25 weight percent diesel fuel.

The 3-arylbenzofuranones antioxidants of the present invention are for example those disclosed in U.S. Pat. Nos. 4,325,863; U.S. Pat. No. 4,388,244; U.S. Pat. No. 5,175,312; U.S. Pat. No. 5,252,643; U.S. Pat. No. 5,216,052; U.S. Pat. No. 5,369,159; U.S. Pat. No. 5,488,117; U.S. Pat. No. 5,356,966; U.S. Pat. No. 5,367,008; U.S. Pat. No. 5,428,162; U.S. Pat. No. 5,428,177; and U.S. Pat. No. 5,516,920; which are hereby incorporated by reference.

Particularly suitable 3-arylbenzofuranones in the present invention are compounds of the formula I

in which, if n is 1,

-   R₁ is unsubstituted or C₁-C₄alkyl-, C₁-C₄alkoxy-, C₁-C₄alkylthio-,     hydroxyl-, halo-, amino-, C₁-C₄alkylamino-, phenylamino- or     di(C₁-C₄alkyl)amino-substituted naphthyl, phenanthryl, anthryl,     5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl,     thienyl, benzo[b]thienyl, naphtho[2,3-b]thienyl, thianthrenyl,     dibenzofuryl, chromenyl, xanthenyl, phenoxathiinyl, pyrrolyl,     imidazolyl, pyrazolyl, pyrazinyl, pyrimidinyl, pyridazinyl,     indolizinyl, isoindolyl, indolyl, indazolyl, purinyl, quinolizinyl,     isoquinolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl,     quinazolinyl, cinnolinyl, pteridinyl, carbazolyl, β-carbolinyl,     phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl,     phenazinyl, isothiazolyl, phenothiazinyl, isoxazolyl, furazanyl,     biphenyl, terphenyl, fluorenyl or phenoxazinyl, or R₁ is a radical     of the formula II     and -   if n is 2, -   R₁ is unsubstituted or C₁-C₄alkyl- or hydroxy-substituted phenylene     or naphthylene; or is —R₁₂—X—R₁₃—, -   R₂, R₃, R₄ and R₅ independently of one another are hydrogen,     chlorine, hydroxyl, C₁-C₂₅alkyl, C₇-C₉phenylalkyl, unsubstituted or     C₁-C₄alkyl-substituted phenyl; unsubstituted or     C₁-C₄alkyl-substituted C₅-C₈cycloalkyl; C₁-C₁₈alkoxy,     C₁-C₁₈alkylthio, C₁-C₄alkylamino, di(C₁-C₄alkyl)amino,     C₁-C₂₅alkanoyloxy, C₁-C₂₅alkanoylamino, C₃-C₂₅alkenoyloxy,     C₃-C₂₅alkanoyloxy which is interrupted by oxygen, sulfur or     ; C₆-C₉cycloalkylcarbonyloxy, benzoyloxy or C₁-C₁₂alkyl-substituted     benzoyloxy; or else the radicals R₂ and R₃ or the radicals R₃ and R₄     or the radicals R₄ and R₅, together with the carbon atoms to which     they are attached, form a benzo ring, R₄ is additionally     —(CH₂)_(p)—COR₁₅ or —(CH₂)_(q)OH or, if R₃, R₅ and R₆ are hydrogen,     R₄ is additionally a radical of the formula III     in which R₁ is defined as indicated above for n=1, -   R₆ is hydrogen or a radical of the formula IV     where R₄ is not a radical of the formula III and R₁ is defined as     indicated above for n=1, -   R₇, R₈, R₉, R₁₀ and R₁₁ independently of one another are hydrogen,     halogen, hydroxyl, C₁-C₂₅alkyl, C₂-C₂₅alkyl interrupted by oxygen,     sulfur or     ; C₁-C₂₅alkoxy, C₂-C₂₅alkoxy interrupted by oxygen, sulfur or     C₁-C₂₅alkylthio, C₃-C₂₅alkenyl, C₃-C₂₅alkenyloxy, C₃-C₂₅alkynyl,     C₃-C₂₅alkynyloxy, C₇-C₉phenylalkyl, C₇-C₉phenylalkoxy, unsubstituted     or C₁-C₄alkyl-substituted phenyl; unsubstituted or     C₁-C₄alkyl-substituted phenoxy; unsubstituted or     C₁-C₄alkyl-substituted C₅-C₈cycloalkyl; unsubstituted or     C₁-C₄alkyl-substituted C₅-C₈cycloalkoxy; C₁-C₄alkylamino,     di(C₁-C₄alkyl)amino, C₁-C₂₅alkanoyl, C₃-C₂₅alkanoyl interrupted by     oxygen, sulfur or     C₁-C₂₅alkanoyloxy, C₃-C₂₅alkanoyloxy interrupted by oxygen, sulfur     or     C₁-C₂₅alkanoylamino, C₃-C₂₅alkenoyl, C₃-C₂₅alkenoyl interrupted by     oxygen, sulfur or     C₃-C₂₅alkenoyloxy, C₃-C₂₅alkenoyloxy interrupted by oxygen, sulfur     or     C₆-C₉cycloalkylcarbonyl, C₆-C₉cycloalkylcarbonyloxy, benzoyl or     C₁-C₁₂alkyl-substituted benzoyl; benzoyloxy or     C₁-C₁₂alkyl-substituted benzoyloxy;     or else, in formula II, the radicals R₇ and -   R₈ or the radicals R₈ and R₁₁, together with the carbon atoms to     which they are attached, form a benzo ring, -   R₁₂ and R₁₃ independently of one another are unsubstituted or     C₁-C₄alkyl-substituted phenylene or naphthylene, -   R₁₄ is hydrogen or C₁-C₈alkyl, -   R₁₅ is hydroxyl,     C₁-C₁₈alkoxy or -   R₁₆ and R₁₇ independently of one another are hydrogen, CF₃,     C₁-C₁₂alkyl or phenyl, or R₁₆ and R₁₇, together with the C atom to     which they are attached, form a C₅-C₈cycloalkylidene ring which is     unsubstituted or substituted from 1 to 3 times by C₁-C₄alkyl; -   R₁₈ and R₁₉ independently of one another are hydrogen, C₁-C₄alkyl or     phenyl, -   R₂₀ is hydrogen or C₁-C₄alkyl, -   R₂₁ is hydrogen, unsubstituted or C₁-C₄alkyl-substituted phenyl;     C₁-C₂₅alkyl, C₂-C₂₅alkyl interrupted by oxygen, sulfur or     C₇-C₉phenylalkyl which is unsubstituted or substituted on the phenyl     radical from 1 to 3 times by C₁-C₄alkyl; C₇-C₂₅phenylalkyl which is     unsubstituted or substituted on the phenyl radical from 1 to 3 times     by C₁-C₄alkyl and interrupted by oxygen, sulfur or     or else the radicals R₂₀ and R₂₁, together with the carbon atoms to     which they are attached, form a C₅-C₁₂cycloalkylene ring which is     unsubstituted or substituted from 1 to 3 times by C₁-C₄alkyl; -   R₂₂ is hydrogen or C₁-C₄alkyl, -   R₂₃ is hydrogen, C₁-C₂₅alkanoyl, C₃-C₂₅alkenoyl, C₃-C₂₅alkanoyl     interrupted by oxygen, sulfur or     C₂-C₂₅alkanoyl substituted by a di(C₁-C₆alkyl)phosphonate group;     C₆-C₉cycloalkylcarbonyl, thenoyl, furoyl, benzoyl or     C₁-C₁₂alkyl-substituted benzoyl; -   R₂₄ and R₂₅ independently of one another are hydrogen or     C₁-C₁₈alkyl, -   R₂₆ is hydrogen or C₁-C₈alkyl, -   R₂₇ is a direct bond, C₁-C₁₈alkylene, C₂-C₁₈alkylene interrupted by     oxygen, sulfur or     C₂-C₁₈alkenylene, C₂-C₂₀alkylidene, C₇-C₂₀phenylalkylidene,     C₅-C₈cycloalkylene, C₇-C₈bicycloalkylene, unsubstituted or     C₁-C₄alkyl-substituted phenylene, or -   R₂₈ is hydroxyl, -   R₂₉ is oxygen, —NH— or -   R₃₀ is C₁-C₁₈alkyl or phenyl, -   R₃₁ is hydrogen or C₁-C₁₈alkyl, -   M is an r-valent metal cation, -   X is a direct bond, oxygen, sulfur or —NR₃₁—, -   n is 1 or 2, -   p is 0, 1 or 2, -   q is 1, 2, 3, 4, 5 or 6, -   r is 1, 2 or 3, and -   s is 0, 1 or 2.

Unsubstituted or C₁-C₄alkyl-, C₁-C₄alkoxy-, C₁-C₄alkylthio-, hydroxyl-, halo-, amino-, C₁-C₄alkylamino-, phenylamino- or di(C₁-C₄alkyl)amino-substituted naphthyl, phenanthryl, anthryl, 5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl, thienyl, benzo[b]thienyl, naphtho[2,3-b]thienyl, thianthrenyl, dibenzofuryl, chromenyl, xanthenyl, phenoxathiinyl, pyrrolyl, imidazolyl, pyrazolyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl, isoindolyl, indolyl, indazolyl, purinyl, quinolizinyl, isoquinolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, pteridinyl, carbazolyl, β-carbolinyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, phenazinyl, isothiazolyl, phenothiazinyl, isoxazolyl, furazanyl, biphenyl, terphenyl, fluorenyl or phenoxazinyl is, for example, 1-naphthyl, 2-naphthyl, 1-phenylamino-4-naphthyl, 1-methylnaphthyl, 2-methylnaphthyl, 1-methoxy-2-naphthyl, 2-methoxy-1-naphthyl, 1-dimethylamino-2-naphthyl, 1,2-dimethyl-4-naphthyl, 1,2-dimethyl-6-naphthyl, 1,2-dimethyl-7-naphthyl, 1,3-dimethyl-6-naphthyl, 1,4-dimethyl-6-naphthyl, 1,5-dimethyl-2-naphthyl, 1,6-dimethyl-2-naphthyl, 1-hydroxy-2-naphthyl, 2-hydroxy-1-naphthyl, 1,4-dihydroxy-2-naphthyl, 7-phenanthryl, 1-anthryl, 2-anthryl, 9-anthryl, 3-benzo[b]thienyl, 5-benzo[b]thienyl, 2-benzo[b]thienyl, 4-dibenzofuryl, 4,7-dibenzofuryl, 4-methyl-7-dibenzofuryl, 2-xanthenyl, 8-methyl-2-xanthenyl, 3-xanthenyl, 2-phenoxathiinyl, 2,7-phenoxathiinyl, 2-pyrrolyl, 3-pyrrolyl, 5-methyl-3-pyrrolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 2-methyl-4-imidazolyl, 2-ethyl-4-imidazolyl, 2-ethyl-5-imidazolyl, 3-pyrazolyl, 1-methyl-3-pyrazolyl, 1-propyl-4-pyrazolyl, 2-pyrazinyl, 5,6-dimethyl-2-pyrazinyl, 2-indolizinyl, 2-methyl-3-isoindolyl, 2-methyl-1-isoindolyl, 1-methyl-2-indolyl, 1-methyl-3-indolyl, 1,5-dimethyl-2-indolyl, 1-methyl-3-indazolyl, 2,7-dimethy-8-purinyl, 2-methoxy-7-methyl-8-purinyl, 2-quinolizinyl, 3-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, isoquinolyl, 3-methoxy-6-isoquinolyl, 2-quinolyl, 6-quinolyl, 7-quinolyl, 2-methoxy-3-quinolyl, 2-methoxy-6-quinolyl, 6-phthalazinyl, 7-phthalazinyl, 1-methoxy-6-phthalazinyl, 1,4-dimethoxy-6-phthalazinyl, 1,8-naphthyridin-2-yl, 2-quinoxalinyl, 6-quinoxalinyl, 2,3-dimethyl-6-quinoxalinyl, 2,3-dimethoxy-6-quinoxalinyl, 2-quinazolinyl, 7-quinazolinyl, 2-dimethylamino-6-quinazolinyl, 3-cinnolinyl, 6-cinnolinyl, 7-cinnolinyl, 3-methoxy-7-cinnolinyl, 2-pteridinyl, 6-pteridinyl, 7-pteridinyl, 6,7-dimethoxy-2-pteridinyl, 2-carbazolyl, 3-carbazolyl, 9-methyl-2-carbazolyl, 9-methyl-3-carbazolyl, β-carbolin-3-yl, 1-methyl-β-carbolin-3-yl, 1-methyl-β-carbolin-6-yl, 3-phenanthridinyl, 2-acridinyl, 3-acridinyl, 2-perimidinyl, 1-methyl-5-perimidinyl, 5-phenanthrolinyl, 6-phenanthrolinyl, 1-phenazinyl, 2-phenazinyl, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 2-phenothiazinyl, 3-phenothiazinyl, 10-methyl-3-phenothiazinyl, 3-isoxazolyl, 4-isoxazoly, 5-isoxazolyl, 4-methyl-3-furazanyl, 2-phenoxazinyl or 10-methyl-2-phenoxazinyl.

Particular preference is given to unsubstituted or C₁-C₄alkyl-, C₁-C₄alkoxy-, C₁-C₄alkylthio-, hydroxyl-, phenylamino- or di(C₁-C₄alkyl)amino-substituted naphthyl, phenanthryl, anthryl, 5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl, thienyl, benzo[b]thienyl, naphtho[2,3-b]thienyl, thianthrenyl, dibenzofuryl, chromenyl, xanthenyl, phenoxathiinyl, pyrrolyl, isoindolyl, indolyl, phenothiazinyl, biphenyl, terphenyl, fluorenyl or phenoxazinyl such as, for example, 1-naphthyl, 2-naphthyl, 1-phenylamino-4-naphthyl, 1-methyinaphthyl, 2-methyinaphthyl, 1-methoxy-2-naphthyl, 2-methoxy-1-naphthyl, 1-dimethylamino-2-naphthyl, 1,2-dimethyl-4-naphthyl, 1,2-dimethyl-6-naphthyl, 1,2-dimethyl-7-naphthyl, 1,3-dimethyl-6-naphthyl, 1,4-dimethyl-6-naphthyl, 1,5-dimethyl-2-naphthyl, 1,6-dimethyl-2-naphthyl, 1-hydroxy-2-naphthyl, 2-hydroxy-1-naphthyl, 1,4-dihydroxy-2-naphthyl, 7-phenanthryl, 1-anthryl, 2-anthryl, 9-anthryl, 3-benzo[b]thienyl, 5-benzo[b]thienyl, 2-benzo[b]-thienyl, 4-dibenzofuryl, 4,7-dibenzofuryl, 4-methyl-7-dibenzofuryl, 2-xanthenyl, 8-methyl-2-xanthenyl, 3-xanthenyl, 2-pyrrolyl, 3-pyrrolyl, 2-phenothiazinyl, 3-phenothiazinyl, 10-methyl-3-phenothiazinyl.

Halogen (halo) is, for example, chlorine, bromine or iodine. Preference is given to chlorine.

Alkanoyl having up to 25 carbon atoms is a branched or unbranched radical such as, for example, formyl, acetyl, propionyl, butanoyl, pentanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, decanoyl, undecanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, pentadecanoyl, hexadecanoyl, heptadecanoyl, octadecanoyl, eicosanoyl or docosanoyl. Preference is given to alkanoyl having 2 to 18, especially 2 to 12, for example 2 to 6 carbon atoms. Particular preference is given to acetyl.

C₂-C₂₅alkanoyl substituted by a di(C₁-C₆alkyl)phosphonate group is, for example, (CH₃CH₂O)₂POCH₂CO—, (CH₃O)₂POCH₂CO—, (CH₃CH₂CH₂CH₂O)₂POCH₂CO—, (CH₃CH₂O)₂POCH₂CH₂CO—, (CH₃O)₂POCH₂CH₂CO—, (CH₃CH₂CH₂CH₂CH₂O)₂POCH₂CH₂CO—, (CH₃CH₂O)₂PO(CH₂)₄CO—, (CH₃CH₂O)₂PO(CH₂)₈CO— or (CH₃CH₂O)₂PO(CH₂)₁₇CO—.

Alkanoyloxy having up to 25 carbon atoms is a branched or unbranched radical such as, for example, formyloxy, acetoxy, propionyloxy, butanoyloxy, pentanoyloxy, hexanoyloxy, hepta-noyloxy, octanoyloxy, nonanoyloxy, decanoyloxy, undecanoyloxy, dodecanoyloxy, trideca-noyloxy, tetradecanoyloxy, pentadecanoyloxy, hexadecanoyloxy, heptadecanoyloxy, octa-decanoyloxy, eicosanoyloxy or docosanoyloxy. Preference is given to alkanoyloxy having 2 to 18, especially 2 to 12, for example 2 to 6 carbon atoms. Particular preference is given to acetoxy.

Alkenoyl having 3 to 25 carbon atoms is a branched or unbranched radical such as, for example, propenoyl, 2-butenoyl, 3-butenoyl, isobutenoyl, n-2,4-pentadienoyl, 3-methyl-2-butenoyl, n-2-octenoyl, n-2-dodecenoyl, iso-dodecenoyl, oleoyl, n-2-octadecenoyl or n-4-octadecenoyl. Preference is given to alkenoyl having 3 to 18, especially 3 to 12, for example 3 to 6, in particular 3 to 4 carbon atoms.

C₃-C₂₅alkenoyl interrupted by oxygen, sulfur or

is, for example, CH₃OCH₂CH₂CH═CHCO— or CH₃OCH₂CH₂OCH═CHCO—.

Alkenoyloxy having 3 to 25 carbon atoms is a branched or unbranched radical such as, for example, propenoyloxy, 2-butenoyloxy, 3-butenoyloxy, isobutenoyloxy, n-2,4-pentadienoyloxy, 3-methyl-2-butenoyloxy, n-2-octenoyloxy, n-2-dodecenoyloxy, iso-dodecenoyloxy, oleoyloxy, n-2-octadecenoyloxy or n-4-octadecenoyloxy. Preference is given to alkenoyloxy having 3 to 18, especially 3 to 12, for example 3 to 6, in particular 3 to 4 carbon atoms.

C₃-C₂₅alkenoyloxy interrupted by oxygen, sulfur or

is, for example,

CH₃OCH₂CH₂CH═CHCOO— or CH₃OCH₂CH₂OCH═CHCOO—.

C₃-C₂₅alkanoyl interrupted by oxygen, sulfur or

is, for example, CH₃—O—CH₂CO—, CH₃—S—CH₂CO—, CH₃—NH—CH₂CO—, CH₃—N(CH₃)—CH₂CO—, CH₃—O—CH₂CH₂—O—CO—, CH₃—(O—CH₂CH₂—)₂O—CH₂CO—, CH₃—(O—CH₂CH₂—)₃O—CH₂CO— or CH₃—(O—CH₂CH₂—)₄O—CH₂CO—.

C₃-C₂₅alkanoyloxy interrupted by oxygen, sulfur or

is, for example, CH₃—O—CH₂COO—, CH₃—S—CH₂COO—, CH₃—NH—CH₂COO—, CH₃—N(CH₃)—CH₂COO—, CH₃—O—CH₂CH₂—O—CH₂COO—, CH₃—(O—CH₂CH₂—)₂O—CH₂COO—, CH₃—(O—CH₂CH₂—)₃O—CH₂COO— or CH₃—(O—CH₂CH₂—)₄O—CH₂COO—.

C₆-C₉cycloalkylcarbonyl is, for example, cyclopentylcarbonyl, cyclohexylcarbonyl, cycloheptylcarbonyl or cyclooctylcarbonyl. Cyclohexylcarbonyl is preferred.

C₆-C₉cycloalkylcarbonyloxy is, for example, cyclopentylcarbonyloxy, cyclohexylcarbonyloxy, cycloheptylcarbonyloxy or cyclooctylcarbonyloxy. Cyclohexylcarbonyloxy is preferred.

C₁-C₁₂alkyl-substituted benzoyl, which preferably carries 1 to 3, especially 1 or 2 alkyl groups, is, for example, o-, m- or p-methylbenzoyl, 2,3-dimethylbenzoyl, 2,4-dimethylbenzoyl, 2,5-d imethylbenzoyl, 2,6-d imethylbenzoyl, 3,4-d imethylbenzoyl, 3,5-dimethylbenzoyl, 2-methyl-6-ethylbenzoyl, 4-tert-butylbenzoyl, 2-ethylbenzoyl, 2,4,6-trimethylbenzoyl, 2,6-dimethyl-4-tert-butylbenzoyl or 3,5-di-tert-butylbenzoyl. Preferred substituents are C₁-C₈alkyl, especially C₁-C₄alkyl.

C₁-C₁₂alkyl-substituted benzoyloxy, which preferably carries 1 to 3, especially 1 or 2 alkyl groups, is, for example, o-, m- or p-methylbenzoyloxy, 2,3-dimethylbenzoyloxy, 2,4-dimethylbenzoyloxy, 2,5-dimethylbenzoyloxy, 2,6-dimethylbenzoyloxy, 3,4-dimethylbenzoyloxy, 3,5-dimethylbenzoyloxy, 2-methyl-6-ethylbenzoyloxy, 4-tert-butylbenzoyloxy, 2-ethyl-benzoyloxy, 2,4,6-trimethylbenzoyloxy, 2,6-dimethyl-4-tert-butylbenzoyloxy or 3,5-di-tert-butylbenzoyloxy. Preferred substituents are C₁-C₈alkyl, especially C₁-C₄alkyl.

Alkyl having up to 25 carbon atoms is a branched or unbranched radical such as, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl or docosyl. One of the preferred meanings of R₂ and R₄ is, for example, C₁-C₁₈alkyl. A particularly preferred meaning of R₄ is C₁-C₄alkyl.

Alkenyl having 3 to 25 carbon atoms is a branched or unbranched radical such as, for example, propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2-butenyl, n-2-octenyl, n-2-dodecenyl, iso-dodecenyl, oleyl, n-2-octadecenyl or n-4-octadecenyl. Preference is given to alkenyl having 3 to 18, especially 3 to 12, for example 3 to 6, in particular 3 to 4 carbon atoms.

Alkenyloxy having 3 to 25 carbon atoms is a branched or unbranched radical such as, for example, propenyloxy, 2-butenyloxy, 3-butenyloxy, isobutenyloxy, n-2,4-pentadienyloxy, 3-methyl-2-butenyloxy, n-2-octenyloxy, n-2-dodecenyloxy, iso-dodecenyloxy, oleyloxy, n-2-octadecenyloxy or n-4-octadecenyloxy. Preference is given to alkenyloxy having 3 to 18, especially 3 to 12, for example 3 to 6, in particular 3 to 4 carbon atoms.

Alkynyl having 3 to 25 carbon atoms is a branched or unbranched radical such as, for example, propynyl (—CH₂—C≡CH ), 2-butynyl, 3-butynyl, n-2-octynyl, or n-2-dodecynyl. Preference is given to alkynyl having 3 to 18, especially 3 to 12, for example 3 to 6, in particular 3 to 4 carbon atoms.

Alkynyloxy having 3 to 25 carbon atoms is a branched or unbranched radical such as, for example, propynyloxy (—OCH₂—C≡CH ), 2-butynyloxy, 3-butynyloxy, n-2-octynyloxy, or n-2-dodecynyloxy. Preference is given to alkynyloxy having 3 to 18, especially 3 to 12, for example 3 to 6, in particular 3 to 4 carbon atoms.

C₂-C₂₅alkyl interrupted by oxygen, sulfur or

is, for example, CH₃—O—CH₂—, CH₃—S—CH₂—, CH₃—NH—CH₂—, CH₃—N(CH₃)—CH₂—, CH₃—O—CH ₂—, CH₃—(O—CH₂CH₂—)₂O—CH₂—, CH₃—(O—CH₂CH₂—)₃O—CH₂— or CH₃—(O—CH₂CH₂—)₄O—CH₂—.

C₇-C₉ phenylalkyl is, for example, benzyl, α-methylbenzyl, α,α-dimethylbenzyl or 2-phenylethyl. Benzyl and α,α-dimethylbenzyl are preferred.

C₇-C₉phenylalkyl which is unsubstituted or substituted on the phenyl radical from 1 to 3 times by C₁-C₄alkyl is, for example, benzyl, α-methylbenzyl, α,α-dimethylbenzyl, 2-phenylethyl, 2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2,4-dimethylbenzyl, 2,6-dimethylbenzyl or 4-tert-butylbenzyl. Benzyl is preferred.

C₇-C₂₅phenylalkyl which is unsubstituted or substituted on the phenyl radical from 1 to 3 times by C₁-C₄alkyl and is interrupted by oxygen, sulfur or

is a branched or unbranched radical such as, for example, phenoxymethyl, 2-methylphenoxymethyl, 3-methyl-phenoxymethyl, 4-methyl phenoxymethyl, 2,4-dimethylphenoxymethyl, 2,3-dimethylphenoxy-methyl, phenylthiomethyl, N-methyl-N-phenylmethyl, N-ethyl-N-phenylmethyl, 4-tert-butyl-phenoxymethyl, 4-tert-butylphenoxyethoxymethyl, 2,4-di-tert-butylphenoxymethyl, 2,4-di-tert-butylphenoxyethoxymethyl, phenoxyethoxyethoxyethoxymethyl, benzyloxymethyl, benzyloxy-ethoxymethyl, N-benzyl-N-ethylmethyl or N-benzyl-N-isopropylmethyl.

C₇-C₉phenylalkoxy is, for example, benzyloxy, α-methylbenzyloxy, α,α-dimethylbenzyloxy or 2-phenylethoxy. Benzyloxy is preferred.

C₁-C₄alkyl-substituted phenyl, which preferably contains 1 to 3, especially 1 or 2 alkyl groups, is, for example, o-, m- or p-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 2-methyl-6-ethylphenyl, 4-tert-butylphenyl, 2-ethylphenyl or 2,6-diethylphenyl.

C₁-C₄alkyl-substituted phenoxy, which preferably contains 1 to 3, especially 1 or 2 alkyl groups, is, for example, o-, m- or p-methylphenoxy, 2,3-dimethylphenoxy, 2,4-dimethylphenoxy, 2,5-dimethylphenoxy, 2,6-dimethylphenoxy, 3,4-dimethylphenoxy, 3,5-dimethylphenoxy, 2-methyl-6-ethylphenoxy, 4-tert-butylphenoxy, 2-ethylphenoxy or 2,6-diethylphenoxy.

Unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkyl is, for example, cyclopentyl, methylcyclopentyl, dimethylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, tert-butylcyclohexyl, cycloheptyl or cyclooctyl. Preference is given to cyclohexyl and tert-butylcyclohexyl.

Unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkoxy is, for example, cyclopentoxy, methylcyclopentoxy, dimethylcyclopentoxy, cyclohexoxy, methylcyclohexoxy, dimethylcyclo-hexoxy, trimethylcyclohexoxy, tert-butylcyclohexoxy, cycloheptoxy or cyclooctoxy. Preference is given to cyclohexoxy and tert-butylcyclohexoxy.

Alkoxy having up to 25 carbon atoms is a branched or unbranched radical such as, for example, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, pentoxy, isopentoxy, hexoxy, heptoxy, octoxy, decyloxy, tetradecyloxy, hexadecyloxy or octadecyloxy. Preference is given to alkoxy having 1 to 12, especially 1 to 8, for example 1 to 6 carbon atoms.

C₂-C₂₅alkoxy interrupted by oxygen, sulfur or

is, for example, CH₃—O—CH₂CH₂O—, CH₃—S—CH₂CH₂O—, CH₃—NH—CH₂CH₂ _(O)—, CH₃—N(CH₃)—CH₂CH₂O—, CH₃—O—CH₂CH₂—O—CH₂CH₂O—, CH₃—(O—CH₂CH₂—)₂O—CH₂CH₂CH₂O— or CH₃—(O—CH₂CH₂—)₄O—CH₂CH₂O—.

Alkylthio having up to 25 carbon atoms is a branched or unbranched radical such as, for example, methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, isobutylthio, pentylthio, isopentylthio, hexylthio, heptylthio, octylthio, decylthio, tetradecylthio, hexadecylthio or octa-decylthio. Preference is given to alkylthio having 1 to 12, especially 1 to 8, for example 1 to 6 carbon atoms.

Alkylamino having up to 4 carbon atoms is a branched or unbranched radical such as, for example, methylamino, ethylamino, propylamino, isopropylamino, n-butylamino, isobutyl-amino or tert-butylamino.

Di(C₁-C₄alkyl)amino also means that the two radicals independently of one another are branched or unbranched, such as, for example, dimethylamino, methylethylamino, diethylamino, methyl-n-propylamino, methylisopropylamino, methyl-n-butylamino, methylisobutylamino, ethylisopropylamino, ethyl-n-butylamino, ethylisobutylamino, ethyl-tert-butylamino, diethylamino, diisopropylamino, isopropyl-n-butylamino, isopropylisobutylamino, di-n-butylamino or diisobutylamino.

Alkanoylamino having up to 25 carbon atoms is a branched or unbranched radical such as, for example, formylamino, acetylamino, propionylamino, butanoylamino, pentanoylamino, hexanoylamino, heptanoylamino, octanoylamino, nonanoylamino, decanoylamino, undeca-noylamino, dodecanoylamino, tridecanoylamino, tetradecanoylamino, pentadecanoylamino, hexadecanoylamino, heptadecanoylamino, octadecanoylamino, eicosanoylamino or doco-sanoylamino. Preference is given to alkanoylamino having 2 to 18, especially 2 to 12, for example 2 to 6 carbon atoms.

C₁-C₁₈alkylene is a branched or unbranched radical such as, for example, methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene or octadecamethylene. Preference is given to C₁-C₁₂alkylene, especially C₁-C₈alkylene.

A C₁-C₄alkyl-substituted C₅-C₁₂cycloalkylene ring, which preferably contains 1 to 3, especially 1 or 2 branched or unbranched alkyl group radicals is, for example, cyclopentylene, methylcyclopentylene, dimethylcyclopentylene, cyclohexylene, methylcyclohexylene, dime-thylcyclohexylene, trimethylcyclohexylene, tert-butylcyclohexylene, cycloheptylene, cyclooc-tylene or cyclodecylene. Preference is given to cyclohexylene and tert-butylcyclohexylene.

C₂-Cl₈alkylene interrupted by oxygen, sulfur or

is, for example, —CH₂—O—CH₂—, —CH₂—S—CH₂—, —CH₂—NH—CH₂—, —CH₂—N(CH₃)—CH₂—, —CH₂—O—CH₂CH₂—O—CH₂—, —CH₂—(O—CH₂CH₂—)₂O—CH₂—, —CH₂—(O—CH₂CH₂—)₃O—CH₂—, —CH₂—(O—CH₂—CH₂CH₂—)₄O—CH₂— or —CH₂CH₂—S—CH₂CH₂—.

C₂-C₁₈alkenylene is, for example, vinylene, methylvinylene, octenylethylene or dodecenylethylene. Preference is given to C₂-C₈alkenylene.

Alkylidene having 2 to 20 carbon atoms is, for example, ethylidene, propylidene, butylidene, pentylidene, 4-methylpentylidene, heptylidene, nonylidene, tridecylidene, nonadecylidene, 1-methylethylidene, 1-ethylpropylidene or 1-ethylpentylidene. Preference is given to C₂-C₈-alkylidene.

Phenylalkylidene having 7 to 20 carbon atoms is, for example, benzylidene, 2-phenylethylidene or 1-phenyl-2-hexylidene. Preference is given to C₇-C₉-phenylalkylidene.

C₅-C₈cycloalkylene is a saturated hydrocarbon group having two free valencies and at least one ring unit and is, for example, cyclopentylene, cyclohexylene, cycloheptylene or cyclooctylene. Preference is given to cyclohexylene.

C₇-C₈bicycloalkylene is, for example, bicycloheptylene or bicyclooctylene.

Unsubstituted or C₁-C₄alkyl-substituted phenylene or naphthylene is, for example, 1,2-, 1,3-, 1,4-phenylene, 1,2-, 1,3-, 1,4-, 1,6-, 1,7-, 2,6- or 2,7-naphthylene. 1,4-Phenylene is preferred.

A C₁-C₄alkyl-substituted C₅-C₈cycloalkylidene ring, which preferably contains 1 to 3, especially 1 or 2 branched or unbranched alkyl group radicals is, for example, cyclopentylidene, methylcyclopentylidene, dimethylcyclopentylidene, cyclohexylidene, methylcyclohexylidene, dimethylcyclohexylidene, trimethylcyclohexylidene, tert-butylcyclohexylidene, cycloheptylidene or cyclooctylidene. Preference is given to cyclohexylidene and tert-butylcyclohexylidene.

A mono-, di- or trivalent metal cation is preferably an alkali metal, alkaline earth metal or aluminium cation, for example, Na⁺, K⁺, Mg⁺⁺, Ca⁺⁺ or Al⁺⁺⁺.

A particularly preferred composition of present invention contains at least one compound of formula 1, wherein, if n=1, R₁ is phenyl which is unsubstituted or substituted in para-position by C₁-C₁₈alkylthio or di(C₁-C₄alkyl)amino; mono- to penta-substituted alkyphenyl containing together a total of at most 18 carbon atoms in the 1 to 5 alkyl substituents; naphthyl, biphenyl, terphenyl, phenanthryl, anthryl, fluorenyl, carbazolyl, thienyl, pyrrolyl, phenothizinyl or 5,6,7,8-tetrahydronaphthyl, each of which is unsubstituted or substituted by C₁-C₄alkyl, C₁-C₄alkoxy, C₁-C₄alkylthio, hydroxy or amino.

Preference is given to compounds of the formula I in which, if n is 2,

-   R₁ is —R₁₂—X—R₁₃—, -   R₁₂ and R₁₃ are phenylene, -   X is oxygen or —NR₃₁—, and -   R₃₁ is C₁-C₄alkyl.

Preference is also given to compounds of the formula I in which, if n is 1, R₁ is unsubstituted or C₁-C₄alkyl-, C₁-C₄alkoxy-, C₁-C₄alkylthio-, hydroxyl-, halo-, amino-, C₁-C₄alkylamino- or di(C₁-C₄-alkyl)amino-substituted naphthyl, phenanthryl, thienyl, dibenzo-furyl, carbazolyl, fluorenyl or a radical of the formula II

R₇, R₈, R₉, R₁₀ and R₁₁ independently of one another are hydrogen, chlorine, bromine, hydroxyl, C₁-C₁₈alkyl, C₂-C₁₈alkyl interrupted by oxygen or sulfur; C₁-C₁₈alkoxy, C₂-C₁₈alkoxy interrupted by oxygen or sulfur; C₁-C₁₈alkylthio, C₃-C₁₂alkenyloxy, C₃-C₁₂alkynyloxy, C₇-C₉phenylalkyl, C₇-C₉phenylalkoxy, unsubstituted or C₁-C₄alkyl-substituted phenyl; phenoxy, cyclohexyl, C₅-C₈cycloalkoxy, C₁-C₄alkylamino, di(C₁-C₄-alkyl)amino, C₁-C₁₂alkanoyl, C₃-C₁₂alkanoyl interrupted by oxygen or sulfur; C₁-C₁₂alkanoyloxy, C₃-C₁₂alkanoyloxy interrupted by oxygen or sulfur; C₁-C₁₂alkanoylamino, C₃-C₁₂alkenoyl, C₃-C₁₂alkenoyloxy, cyclohexylcarbonyl, cyclohexylcarbonyloxy, benzoyl or C₁-C₄alkyl-substituted benzoyl; benzoyloxy or C₁-C₄alkyl-substituted benzoyloxy;

or else in formula II the radicals R₇ and R₈ or the radicals R₈ and R₁₁, together with the carbon atoms to which they are attached, form a benzo ring,

-   R₁₅ is hydroxyl, C₁-C₁₂alkoxy or -   R₁₈ and R₁₉ independently of one another are hydrogen or C₁-C₄alkyl, -   R₂₀ is hydrogen, -   R₂₁ is hydrogen, phenyl, C₁-C₁₈alkyl, C₂-C₁₈alkyl interrupted by     oxygen or sulfur; -   C₇-C₉phenylalkyl, C₇-C₁₈-phenylalkyl which is unsubstituted or     substituted on the phenyl radical from 1 to 3 times by C₁-C₄alkyl     and is interrupted by oxygen or sulfur, or else the radicals R₂₀ and     R₂₁, together with the carbon atoms to which they are attached, form     a cyclohexylene ring which is unsubstituted or substituted from 1 to     3 times by C₁-C₄alkyl, -   R₂₂ is hydrogen or C₁-C₄alkyl, -   R₂₃ is hydrogen, C₁-C₁₈alkanoyl, C₃-C₁₈alkenoyl, C₃-C₁₂alkanoyl     interrupted by oxygen or sulfur; -   C₂-C₁₂alkanoyl substituted by a di(C₁-C₆-alkyl)phosphonate group;     C₆-C₉cycloalkylcarbonyl, -   R₂₄ and R₂₅ independently of one another are hydrogen or     C₁-C₁₂alkyl, -   R₂₆ is hydrogen or C₁-C₄alkyl, -   R₂₇ is C₁-C₁₂alkylene, C₂-C₈alkenylene, C₂-C₈alkylidene,     C₇-C₁₂phenylalkylidene, C₅-C₈cycloalkylene or phenylene, -   R₂₈ is hydroxyl, C₁-C₁₂alkoxy or -   R₂₉ is oxygen or —NH—, -   R₃₀ is C₁-C₁₈alkyl or phenyl, and -   s is 1 or 2.

Preference is likewise given to compounds of the formula I in which, if n is 1, R₁ is phenanthryl, thienyl, dibenzofuryl, unsubstituted or C₁-C₄alkyl-substituted carbazolyl; or is fluorenyl; or R₁ is a radical of the formula II

-   R₇, R₈, R₉, R₁₀ and R₁₁ independently of one another are hydrogen,     chlorine, hydroxyl, -   C₁-C₁₈alkyl, C₁-C₁₈alkoxy, C₁-C₁₈alkylthio, C₃-C₄alkenyloxy,     C₃-C₄alkinyloxy, C₂-C₁₈alkanoyloxy, phenyl, benzoyl, benzoyloxy or -   R₂₀ is hydrogen, -   R₂₁ is hydrogen, phenyl or C₁-C₁₈alkyl, or else the radicals R₂₀ and     R₂₁, together with the carbon atoms to which they are attached, form     a cyclohexylene ring which is unsubstituted or substituted from 1 to     3 times by C₁-C₄alkyl, -   R₂₂ is hydrogen or C₁-C₄alkyl, and -   R₂₃ is hydrogen, C₁-C₁₈alkanoyl or benzoyl.

Particular preference is given to compounds of the formula I in which, if n is 1,

-   R₇, R₈, R₉, R₁₀ and R₁₁ independently of one another are hydrogen,     C₁-C₄alkylthio or phenyl.

Of particular interest is a composition containing at least one compound of the formula I in which R₂, R₃, R₄ and R₅ independently of one another are hydrogen, chlorine, C₁-C₁₈alkyl, benzyl, phenyl, C₅-C₈cycloalkyl, C₁-C₁₈alkoxy, C₁-C₁₈alkylthio, C₁-C₁₈alkanoyloxy, C₁-C₁₈alkanoylamino, C₃-C₁₈alkenoyloxy or benzoyloxy; or else the radicals R₂ and R₃ or the radicals R₃ and R₄ or the radicals R₄ and R₅, together with the carbon atoms to which they are attached, form a benzo ring, R₄ is additionally —(CH₂)_(p)—COR₁₅ or —(CH₂)_(q)OH, or, if R₃, R₅ and R₆ are hydrogen, R₄ is additionally a radical of the formula III,

-   R₁₅ is hydroxyl, C₁-C₁₂alkoxy or -   R₁₆ and R₁₇ are methyl groups or, together with the C atom to which     they are attached, form a C₅-C₈cycloalkylidene ring which is     unsubstituted or substituted from 1 to 3 times by C₁-C₄alkyl, -   R₂₄ and R₂₅ independently of one another are hydrogen or     C₁-C₁₂alkyl, -   p is 1 or 2, and -   q is 2, 3, 4, 5 or 6.

Also of particular interest is a composition containing at least one compound of the formula I in which at least two of the radicals R₂, R₃, R₄ and R₅ are hydrogen.

Of special interest is a composition containing at least one compound of the formula I in which R₃ and R₅ are hydrogen.

Of very special interest is composition containing at least one compound of the formula I in which

-   R₂ is C₁-C₄alkyl, -   R₃ is hydrogen, -   R₄ is C₁-C₄alkyl or, if R₆ is hydrogen, R₄ is additionally a radical     of the formula III, -   R₅ is hydrogen, and -   R₁₆ and R₁₇, together with the C atom to which they are attached,     form a cyclohexylidene ring.

The following compounds are examples of the benzofuran-2-one type which are particularly suitable in the composition of the present invention: 3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-tert -butyl-benzofuran-2-one; 5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy) phenyl]benzofuran-2-one; 3,3′-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]-phenylbenzofuran-2-one]; 5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one; 3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2-one; 3-(3,5-dimethyl-4-pivaloyloxy-phenyl)-5,7-di-tert-butyl-benzofuran-2-one; 5,7-di-tert-butyl-3-phenylbenzofuran-2-one; 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)-benzofuran-2-one; 5,7-di-tert-butyl-3-(2,3-dimethylphenyl)benzofuran-2-one.

Also of special interest is a composition containing at least one compound of the formula V

in which

-   R₂ is hydrogen or C₁-C₆alkyl, -   R₃ is hydrogen, -   R₄ is hydrogen or C₁-C₆alkyl, -   R₅ is hydrogen, R₇, R₈, R₉, R₁₀ and R₁₁ independently of one another     are hydrogen, C₁-C₄alkyl or C₁-C₄alkoxy, with the proviso that at     least two of the radicals R₇, R₈, R₉, R₁₀ or R₁₁ are hydrogen.

Very particular preference is given to a composition containing at least one compound of the formula Va or Vb

or a mixture of the two compounds of the formula Va and Vb.

The present sterically hindered amine stabilizers contain at least one moiety of formula

where G₁, G₂, G₃, G₄ and G₅ are independently alkyl of 1 to 8 carbon atoms or G₁ and G₂ or G₃ and G₄ together are pentamethylene.

The hindered amines are disclosed for example in U.S. Pat. Nos. 5,004,770, 5,204,473, 5,096,950, 5,300,544, 5,112,890, 5,124,378, 5,145,893, 5,216,156, 5,844,026, 5,980,783, 6,046,304, 6,117,995, 6,271,377, 6,297,299, 6,392,041, 6,376,584 and 6,472,456, and U.S. application Ser. Nos. 09/714,717, filed Nov. 16, 2000 and U.S. application Ser. No. 10/485,377, filed Aug. 6, 2002. The relevant disclosures of these patents and applications are hereby incorporated by reference.

U.S. Pat. Nos. 6,271,377, 6,392,041 and U.S. Pat. No. 6,376,584, cited above disclose hindered hydroxyalkoxyamine stabilizers.

-   -   Suitable hindered amines include for example:     -   1)         1-cyclohexyloxy-2,2,6,6-tetramethyl-4-octadecylaminopiperidine,     -   2) bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate,     -   3) bis(1-acetoxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate,     -   4) bis(1,2,2,6,6-pentamethyl-4-yl) sebacate,     -   5) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)         sebacate,     -   6) bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;     -   7) bis(1-acyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate,     -   8) bis(1,2,2,6,6-pentamethyl-4-piperidyl)         n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate     -   9)         2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-6-(2-hydroxy         -ethylamino-s-triazine,     -   10) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)         adipate,     -   11)         2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin-4-yl)butylamino]-6-chloro-s-triazine,     -   12)         1-(2-hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpiperidine,     -   13)         1-(2-hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiperidine,     -   14)         1-(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetramethylpiperidine,     -   15)         bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)         sebacate,     -   16)         bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)         adipate,     -   17)         2,4-bis{N-[1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N-butyl         -amino}-6-(2-hydroxyethylamino)-s-triazine,     -   18) 4-benzoyl-2,2,6,6-tetramethylpiperidine,     -   19) di-(1,2,2,6,6-pentamethylpiperidin-4-yl)         p-methoxybenzylidenemalonate,     -   20) 4-stearyloxy-2,2,6,6-tetramethylpiperidine,     -   21) bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate,     -   22) 1,2,2,6,6-pentamethyl-4-aminopiperidine,     -   23)         2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane,     -   24) tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate,     -   25)         tris(2-hydroxy-3-(amino-(2,2,6,6-tetramethylpiperidin-4-yl)propyl)         nitrilotriacetate,     -   26)         tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate,     -   27)         tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate,     -   28) 1,1′-(1,2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone),     -   29)         3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione,     -   30)         8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione,     -   31)         3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione,     -   32)         3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione,     -   33)         N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine,     -   34) the reaction product of         2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin-4-yl)butylamino]-6-chloro         -s-triazine with N,N′-bis(3-aminopropyl)ethylenediamine),     -   35) the condensate of         1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and         succinic acid,     -   36) linear or cyclic condensates of         N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine         and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine,     -   37) linear or cyclic condensates of         N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine         and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine,     -   38) linear or cyclic condensates of         N,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine         and 4-morpholino-2,6-dichloro-1,3,5-triazine,     -   39) linear or cyclic condensates of         N,N′-bis-(1,2,2,6,6-pentamethyl-4-piperidyl)-hexamethylenediamine         and 4-morpholino-2,6-dichloro-1,3,5-triazine,     -   40) the condensate of         2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine         and 1,2-bis(3-aminopropylamino)ethane,     -   41) the condensate of         2-chloro4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine         and 1,2-bis-(3-aminopropylamino)ethane,     -   42) a reaction product of         7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro         [4,5]decane and epichlorohydrin,     -   43)         poly[methyl,(3-oxy-(2,2,6,6-tetramethylpiperidin-4-yl)propyl)]         siloxane, CAS#182635-99-0,     -   44) reaction product of maleic acid         anhydride-C₁₈-C₂₂-α-olefin-copolymer with         2,2,6,6-tetramethyl-4-aminopiperidine,     -   45) the oligomeric compound which is the condensation product of         4,4′-hexamethylene-bis(amino-2,2,6,6-tetramethylpiperidine) and         2,4-dichloro-6-[(2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine         end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine,     -   46) the oligomeric compound which is the condensation product of         4,4′-hexamethylene-bis(amino-1,2,2,6,6-pentaamethylpiperidine)         and         2,4-dichloro-6-[(1,2,2,6,6-pentaamethyl-piperidin-4-yl)butylamino]-s-triazine         end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine,     -   47) the oligomeric compound which is the condensation product of         4,4′-hexamethylene-bis(amino-1-propoxy-2,2,6,6-tetramethylpiperidine)         and 2,4-dichloro-6-[(1-propoxy-2,2,6,6-tetra-methylpiperin         -4-yl)butylamino]-s-triazine end-capped with         2-chloro-4,6-bis(dibutylamino)-s-triazine,     -   48) the oligomeric compound which is the condensation product of         4,4′-hexamethylene-bis(amino-1-acyloxy-2,2,6,6-tetramethylpiperidine)         and 2,4-dichloro-6-[(1-acyloxy-2,2,6,6-tetra-methylpiperin         -4-yl)butylamino]-s-triazine end-capped with         2-chloro-4,6-bis(dibutylamino)-s-triazine and     -   49) product obtained by reacting a product, obtained by reacting         1,2-bis(3-amino-propylamino) ethane with cyanuric chloride, with         (2,2,6,6-tetramethylpiperidin-4-yl)butylamine.

Also included are the sterically hindered N—H, N-methyl, N-methoxy, N-propoxy, N-octyloxy, N-cyclohexyloxy, N-acyloxy and N-(2-hydroxy-2-methylpropoxy) analogues of any of the above mentioned compounds. For example, replacing an N—H hindered amine with an N-methyl hindered amine would be employing the N-methyl analogue in place of the N—H.

For illustrative purposes, some of the structures for the above-named compounds are shown below:

The hindered phenolic antioxidants are for example

1.1. Alkylated monophenols, for example 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(α-methylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1-methylundec-1-yl)phenol, 2,4-dimethyl-6-(1-methylheptadec-1-yl)phenol, 2,4-dimethyl-6-(1-methyltridec-1-yl)phenol and mixtures thereof.

1.2. Alkylthiomethylphenols, for example 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4-nonylphenol.

1.3. Hydroquinones and alkylated hydroquinones, for example 2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, bis-(3,5-di-tert-butyl-4-hydroxyphenyl)adipate.

1.4. Tocopherols, for example α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol and mixtures thereof (Vitamin E).

1.5. Hydroxylated thiodiphenyl ethers, for example 2,2′-thiobis(6-tert-butyl-4-methylphenol), 2,2′-thiobis(4-octylphenol), 4,4′-thiobis(6-tert-butyl-3-methylphenol), 4,4′-thiobis(6-tert -butyl-2-methylphenol), 4,4′-thiobis-(3,6-di-sec-amylphenol), 4,4′-bis(2,6-dimethyl-4-hydroxyphenyl) disulfide.

1.6. Alkylidenebisphenols, for example 2,2′-methylenebis(6-tert-butyl-4-methylphenol), 2,2′-methylenebis (6-tert-butyl-4-ethylphenol), 2,2′-methylenebis[4-methyl-6-(α-methylcyclohexyl)phenol], 2,2′-methylenebis(4-methyl-6-cyclohexylphenol), 2,2′-methylenebis(6-nonyl-4-methylphenol), 2,2′-methylenebis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2′-methylenebis[6-(α-methylbenzyl)-4-nonylphenol], 2,2′-methylenebis[6-(a,a-dimethylbenzyl)-4-nonylphenol], 4,4′-methylenebis(2,6-di-tert -butylphenol), 4,4′-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-butyl-4-hydroxy -2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy -2-methyl-phenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl) butyrate], bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene, bis[2-(3′tert-butyl-2-hydroxy-5-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1,1-bis-(3,5-dimethyl-2-hydroxyphenyl) butane, 2,2-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis-(5-tert-butyl-4-hydroxy 2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.

1.7. Benzyl compounds, for example 3,5,3′,5′-tetra-tert-butyl-4,4′-dihydroxydibenzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert -butylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, 1,3,5-tri-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, di-(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide,3,5-di-tert-butyl-4-hydroxybenzyl-mercapto-acetic acid isooctyl ester, bis-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiol terephthalate, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid dioctadecyl ester and 3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid monoethyl ester, calcium-salt.

1.8. Hydroxybenzylated malonates, for example dioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hydroxybenzyl)-malonate, di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malonate, di-dodecylmercaptoethyl-2,2-bis-(3,5-di -tert-butyl-4-hydroxybenzyl)malonate, bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl -4-hydroxybenzyl)malonate.

1.9. Aromatic hydroxybenzyl compounds, for example 1 ,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

1.10. Triazine compounds, for example 2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino) -1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 2,4,6-tris-(3,5-di-tert -butyl-4-hydroxyphenoxy)-1,2,3-triazine, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxy-benzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxy-phenylpropionyl)-hexahydro-1,3,5-triazine, 1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.

1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethyl-3,5-di-tert -butyl-4-hydroxybenzylphosphonate, dioctadecyl3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

1.12. Acylaminophenols, for example 4-hydroxy-lauric acid anilide, 4-hydroxy-stearic acid anilide, 2,4-bis-octylmercapto-6-(3,5-tert-butyl-4-hydroxyanilino)-s-triazine and octyl-N-(3,5-di-tert -butyl-4-hydroxyphenyl)-carbamate.

1.13. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glyco, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.14. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexane-diol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N′-bis-(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethyl-olpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.15. Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)ox-amide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.17. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid e.g. N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide, N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamide, N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazide, N,N′-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide (Naugard®×L-1 supplied by Uniroyal).

Each of the 3-arylbenzofuranone and hindered amine light stabilizers, and the optional phenolic antioxidant, are employed at levels of about 5 ppm to about 5000 ppm, for example from about 50 ppm to about 5000 ppm, for example from about 100 to about 5000 ppm by weight, based on the weight of the biodiesel fuel. For example, each of the present additives are present from about 150 to about 4000 ppm, from about 200 to about 3000 ppm, or from about 250 to about 2500 ppm by weight, based on the weight of the biodiesel fuel. In certain instances, the levels may be as high as about 1%, about 2% or about 3% by weight, based on the weight of the biodiesel fuel.

The present stabilized biodiesel fuels exhibit increased storage stability vs. unstabilized samples. Degradation of biodiesel fuels under the conditions of heat, light or oxygen is observed by the formation of carboxylic acids, peroxides, aldehydes and alcohols.

EXAMPLES

The Rancimat test, developed by the food industry, is employed to test the oxidative stability of soy biodiesel (methyl ester of soy fatty acid). A 3.0 g sample of soy biodiesel is held at 111.7° C. and exposed to a bubbling stream of air (10 liters per hour). The sample vessel is vented to a secondary container, where the off-gases are bubbled through 60 mL of distilled water. The test measures the volatile oxidation decomposition products such as peroxides, alcohols, aldehydes and carboxylic acids. The volatile decomposition products (chiefly formic acid) are swept through the sample vessel and vented into the secondary container where they are trapped by the distilled water. The conductivity of the water is constantly monitored as a function of time through use of an electrode. The inflection point (not a specific value) of the conductivity curve is the measured induction time. It should be pointed out that some samples will be highly conductive before the inflection point is achieved, while others will only be slightly conductive. An increase of the induction time indicates an increase in oxidative stability. Results are in the table below. Levels of additive are in weight percent based on the weight of the biodiesel. Rancimat Induction Time sample additive Induction Time (hours) 1 none 5.0 (control) 2  250 ppm A 6.6 3 2500 ppm A 8.8 4 2500 ppm B 12.7 Additive A is bis-(1,1 ,2,2,6,6-pentamethyl-4-piperidyl) sebacate; B is 3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

A 6 hour induction time is necessary to meet the EN 14214 specification. 

1. A biodiesel fuel composition stabilized against the deleterious effects of heat, light and oxygen, which composition comprises a biodiesel fuel and an effective stabilizing amount of one or more additives selected from the group consisting of the 3-arylbenzofuranone stabilizers and the hindered amine light stabilizers and optionally, one or more additives selected from the group consisting of the hindered phenolic antioxidants.
 2. A composition according to claim 1 comprising one or more 3-arylbenzofuranone stabilizers of formula I

in which, if n is 1, R₁ is unsubstituted or C₁-C₄alkyl-, C₁-C₄alkoxy-, C₁-C₄alkylthio-, hydroxyl-, halo-, amino-, C₁-C₄alkylamino-, phenylamino- or di(C₁-C₄alkyl)amino-substituted naphthyl, phenanthryl, anthryl, 5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl, thienyl, benzo[b]thienyl, naphtho[2,3-b]thienyl, thianthrenyl, dibenzofuryl, chromenyl, xanthenyl, phenoxathiinyl, pyrrolyl, imidazolyl, pyrazolyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl, isoindolyl, indolyl, indazolyl, purinyl, quinolizinyl, isoquinolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, pteridinyl, carbazolyl, β-carbolinyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, phenazinyl, isothiazolyl, phenothiazinyl, isoxazolyl, furazanyl, biphenyl, terphenyl, fluorenyl or phenoxazinyl, or R₁ is a radical of the formula II

and if n is 2, R₁ is unsubstituted or C₁-C₄alkyl- or hydroxy-substituted phenylene or naphthylene; or is -R₁₂—X—R₁₃—, R₂, R₃, R₄ and R₅ independently of one another are hydrogen, chlorine, hydroxyl, C₁-C₂₅alkyl, C₇-C₉ phenylalkyl, unsubstituted or C₁-C₄alkyl-substituted phenyl; unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkyl; C₁-C₁₈alkoxy, C₁-C₁₈alkylthio, C₁-C₄alkylamino, di(C₁-C₄alkyl)amino, C₁-C₂₅alkanoyloxy, C₁-C₂₅alkanoylamino, C₃-C₂₅alkenoyloxy, C₃-C₂₅alkanoyloxy which is interrupted by oxygen, sulfur or C₆-C₉cycloalkylcarbonyloxy, benzoyloxy or C₁-C₁₂alkyl-substituted benzoyloxy; or else the radicals R₂ and R₃ or the radicals R₃ and R₄ or the radicals R₄ and R₅, together with the carbon atoms to which they are attached, form a benzo ring, R₄ is additionally —(CH₂)_(p)—COR₁₅ or —(CH₂)_(q)OH or, if R₃, R₅ and R₆ are hydrogen, R₄ is additionally a radical of the formula III

in which R₁ is defined as indicated above for n=1, R₆ is hydrogen or a radical of the formula IV

where R₄ is not a radical of the formula III and R₁ is defined as indicated above for n=1, R₇, R₈, R₉, R₁₀, and R₁₁ independently of one another are hydrogen, halogen, hydroxyl, C₁-C₂₅alkyl, C₂-C₂₅alkyl interrupted by oxygen, sulfur or

C₁-C₂₅alkoxy, C₂-C₂₅alkoxy interrupted by oxygen, sulfur or

C₁-C₂₅alkylthio, C₃-C₂₅alkenyl, C₃-C₂₅alkenyloxy, C₃-C₂₅alkynyl, C₃-C₂₅alkynyloxy, C₇-C₉phenylalkyl, C₇-C₉phenylalkoxy, unsubstituted or C₁-C₄alkyl-substituted phenyl; unsubstituted or C₁-C₄alkyl-substituted phenoxy; unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkyl; unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkoxy; C₁-C₄alkylamino, di(C₁-C₄alkyl)amino, C₁-C₂₅alkanoyl, C₃-C ₂₅alkanoyl interrupted by oxygen, sulfur or

C₁-C₂₅alkanoyloxy, C₃-C₂₅alkanoyloxy interrupted by oxygen, sulfur or

C₁-C₂₅alkanoylamino, C₃-C₂₅alkenoyl, C₃-C₂₅alkenoyl interrupted by oxygen, sulfur or

C₃-C₂₅alkenoyloxy, C₃-C₂₅alkenoyloxy interrupted by oxygen, sulfur or

C₆-C₉cycloalkylcarbonyl, C₆-C₉cycloalkylcarbonyloxy, benzoyl or C₁-C₁₂alkyl-substituted benzoyl; benzoyloxy or C₁-C₁₂alkyl-substituted benzoyloxy;

or else, in formula II, the radicals R₇ and R₈ or the radicals R₈ and R₁₁, together with the carbon atoms to which they are attached, form a benzo ring, R₁₂ and R₁₃ independently of one another are unsubstituted or C₁-C₄alkyl-substituted phenylene or naphthylene, R₁₄ is hydrogen or C₁-C₈alkyl, R₁₅ is hydroxyl,

R₁₆ and R₁₇ independently of one another are hydrogen, CF₃, C₁-C₁₂alkyl or phenyl, or R₁₆ and R₁₇, together with the C atom to which they are attached, form a C₅-C₈cycloalkylidene ring which is unsubstituted or substituted from 1 to 3 times by C₁-C₄alkyl; R₁₈ and R₁₉ independently of one another are hydrogen, C₁-C₄alkyl or phenyl, R₂₀ is hydrogen or C₁-C₄alkyl, R₂₁ is hydrogen, unsubstituted or C₁-C₄alkyl-substituted phenyl; C₁-C₂₅alkyl, C₂-C₂₅alkyl interrupted by oxygen, sulfur or

C₇-C₉phenylalkyl which is unsubstituted or substituted on the phenyl radical from 1 to 3 times by C₁-C₄alkyl; C₇-C₂₅phenylalkyl which is unsubstituted or substituted on the phenyl radical from 1 to 3 times by C₁-C₄alkyl and interrupted by oxygen, sulfur or

or else the radicals R₂₀ and R₂₁, together with the carbon atoms to which they are attached, form a C₅-C₁₂cycloalkylene ring which is unsubstituted or substituted from 1 to 3 times by C₁-C₄alkyl; R₂₂ is hydrogen or C₁-C₄alkyl, R₂₃ is hydrogen, C₁-C₂₅alkanoyl, C₃-C₂₅alkenoyl, C₃-C₂₅alkanoyl interrupted by oxygen, sulfur or

C₂-C₂₅alkanoyl substituted by a di(C₁-C₆alkyl)phosphonate group; C₆-C₉cycloalkylcarbonyl, thenoyl, furoyl, benzoyl or C₁-C₁₂alkyl-substituted benzoyl;

R₂₄ and R₂₅ independently of one another are hydrogen or C₁-C₁₈alkyl, R₂₆ is hydrogen or C₁-C₈alkyl, R₂₇ is a direct bond, C₁-C₁₈alkylene, C₂-C₁₈alkylene interrupted by oxygen, sulfur or

C₂-C₁₈alkenylene, C₂-C₂₀alkylidene, C₇-C₂₀phenylalkylidene, C₅-C₈cycloalene, C₇-C₈bicycloalkylene, unsubstituted or C₁-C₄alkyl-substituted phenylene, or

R₂₈ is hydroxyl,

R₂₉ is oxygen, —NH— or

R₃₀ is C₁-C₁₈alkyl or phenyl, R₃₁ is hydrogen or C₁-C₁₈alkyl, M is an r-valent metal cation, X is a direct bond, oxygen, sulfur or 13 NR₃₁—, n is 1 or 2, p is 0, 1 or 2, q is 1, 2, 3, 4, 5 or 6, r is 1, 2, or 3, and s is 0, 1 or
 2. 3. A composition according to claim 2 wherein the 3-arylbenzofuranones are of formula I wherein n=1, R₁ is phenyl which is unsubstituted or substituted in para-position by C₁-C₁₈alkylthio or di(C₁-C₄alkyl)amino; mono- to penta-substituted alkyphenyl containing together a total of at most 18 carbon atoms in the 1 to 5 alkyl substituents; naphthyl, biphenyl, terphenyl, phenanthryl, anthryl, fluorenyl, carbazolyl, thienyl, pyrrolyl, phenothizinyl or 5,6,7,8-tetrahydronaphthyl, each of which is unsubstituted or substituted by C₁-C₄alkyl, C₁-C₄alkoxy, C₁-C₄alkylthio, hydroxy or amino.
 4. A composition according to claim 2 wherein the 3-arylbenzofuranones are of formula I wherein n is 2, R₁ is —R₁₂—X—R₁₃—, R₁₂ and R₁₃ are phenylene, X is oxygen or —NR ₃₁—, and R₃₁ is C₁-C₄alkyl.
 5. A composition according to claim 2 wherein the 3-arylbenzofuranones are selected from the group consisting of 3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-tert-butyl-benzofuran-2-one; 5,7-di-tert-butyl -3-[4-(2-stearoyloxyethoxy)phenyl]benzofuran-2-one; 3,3′-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one]; 5,7-di-tert-butyl-3(4-ethoxyphenyl) benzofuran-2-one; 3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2-one; 3-(3,5-dimethyl-4-pivaloyloxy-phenyl)-5,7-di-tert-butyl-benzofuran-2-one; 5,7-di-tert-butyl-3-phenylbenzofuran-2-one; 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)-benzofuran-2-one and 5,7-di-tert-butyl-3-(2,3-dimethylphenyl)-benzofuran-2-one.
 6. A composition according to claim 1 comprising one or more hindered amine light stabilizers that contain at least one moiety of formula

where G₁, G₂, G₃, G₄ and G₅ are independently alkyl of 1 to 8 carbon atoms or G₁ and G₂ or G₃ and G₄ together are pentamethylene.
 7. A composition according to claim 6 where the hindered amine stabilizers are selected from the group consisting of 1) 1-cyclohexyloxy-2,2,6,6-tetramethyl-4-octadecylaminopiperidine, 2) bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 3) bis(1-acetoxy-2,2,6,6-tetramethylpiperidin4-yl) sebacate, 4) bis(1,2,2,6,6-pentamethyl-4-yl) sebacate, 5) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 6) bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate; 7) bis(1-acyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 8) bis(1,2,2,6,6-pentamethyl-4-piperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate 9) 2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-6-(2-hydroxy-ethylamino-s-triazine, 10) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) adipate, 11) 2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin4-yl)butylamino]-6-chloro-s-triazine, 12) 1-(2-hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpiperidine, 13) 1-(2-hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiperidine, 14) 1-(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetramethylpiperidine, 15) bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 16) bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl) adipate, 17) 2,4-bis{N-[1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N -butyl-amino}-6-(2-hydroxyethylamino)-s-triazine, 18) 4-benzoyl-2,2,6,6-tetramethylpiperidine, 19) di-(1,2,2,6,6-pentamethylpiperidin-4-yl) p-methoxybenzylidenemalonate, 20) 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 21) bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, 22) 1,2,2,6,6-pentamethyl-4-aminopiperidine, 23) 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane, 24) tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate, 25) tris(2-hydroxy-3-(amino-(2,2,6,6-tetramethylpiperidin-4-yl)propyl) nitrilotriacetate, 26) tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 27) tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 28) 1,1′-(1,2-ethanedlyl)-bis(3,3,5,5-tetramethylpiperazinone), 29) 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione, 30) 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione, 31) 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione, 32) 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione, 33) N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine, 34) the reaction product of 2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin-4-yl)butylamino]-6-chloro-s-triazine with N,N′-bis(3-aminopropyl)ethylenediamine), 35) the condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, 36) linear or cyclic condensates of N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine, 37) linear or cyclic condensates of N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, 38) linear or cyclic condensates of N,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, 39) linear or cyclic condensates of N,N′-bis-(1,2,2,6,6-pentamethyl-4-piperidyl)-hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, 40) the condensate of 2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, 41) the condensate of 2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine and 1,2-bis-(3-aminopropylamino)ethane, 42) a reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4,5]decane and epichlorohydrin, 43) poly[methyl,(3-oxy-(2,2,6,6-tetramethylpiperidin-4-yl)propyl)] siloxane, CAS#182635-99-0, 44) reaction product of maleic acid anhydride-C₁₈-C₂₂-α-olefin-copolymer with 2,2,6,6-tetramethyl-4-aminopiperidine, 45) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis(amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, 46) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis(amino-1,2,2,6,6-pentaamethylpiperidine) and 2,4-dichloro-6-[(1,2,2,6,6-pentaamethyl-piperidin-4-yl)butylamino]-s-triazine end -capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, 47) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis(amino-1-propoxy-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1-propoxy-2,2,6,6-tetra-methylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, 48) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis(amino-1-acyloxy-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1-acyloxy-2,2,6,6-tetra-methylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine and 49) product obtained by reacting a product, obtained by reacting 1,2-bis(3-amino-propylamino)ethane with cyanuric chloride, with (2,2,6,6-tetramethylpiperidin-4-yl)butylamine.
 8. A composition according to claim 6 where the hindered amine is an N—H, N-methyl, N-methoxy, N-propoxy, N-octyloxy, N-cyclohexyloxy, N-acyloxy or an N-(2-hydroxy-2-methyl-propoxy) substituted amine.
 9. A composition according to claim 1 comprising one or more 3-arylbenzofuranone stabilizers and one or more hindered phenolic antioxidants.
 10. A composition according to claim 9 where the 3-arylbenzofuranone stabilizers are of formula I

in which, if n is 1, R₁ is unsubstituted or C₁-C₄alkyl-, C₁-C₄alkoxy-, C₁-C₄alkylthio-, hydroxyl-, halo-, amino-, C₁-C₄alkylamino-, phenylamino- or di(C₁-C₄alkyl)amino-substituted naphthyl, phenanthryl, anthryl, 5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl, thienyl, benzo[b]thienyl, naphtho[2,3-b]thienyl, thianthrenyl, dibenzofuryl, chromenyl, xanthenyl, phenoxathiinyl, pyrrolyl, imidazolyl, pyrazolyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl, isoindolyl, indolyl, indazolyl, purinyl, quinolizinyl, isoquinolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, pteridinyl, carbazolyl, β-carbolinyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, phenazinyl, isothiazolyl, phenothiazinyl, isoxazolyl, furazanyl, biphenyl, terphenyl, fluorenyl or phenoxazinyl, or R₁ is a radical of the formula II

and if n is 2, R₁ is unsubstituted or C₁-C₄alkyl- or hydroxy-substituted phenylene or naphthylene; or is —R₁₂—X—R₁₃—, R₂, R₃, R₄ and R₅ independently of one another are hydrogen, chlorine, hydroxyl, C₁-C₂₅alkyl, C₇-C₉phenylalkyl, unsubstituted or C₁-C₄alkyl-substituted phenyl; unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkyl; C₁-C₁₈alkoxy, C₁-C₁₈alkylthio, C₁-C₄alkylamino, di(C₁-C₄alkyl)amino, C₁-C₂₅alkanoyloxy, C₁-C₂₅alkanoylamino, C₃-C₂₅alkenoyloxy, C₃-C₂₅alkanoyloxy which is interrupted by oxygen, sulfur or

C₆-C₉cycloalkylcarbonyloxy, benzoyloxy or C₁-C₁₂alkyl-substituted benzoyloxy; or else the radicals R₂ and R₃ or the radicals R₃ and R₄ or the radicals R₄ and R₅, together with the carbon atoms to which they are attached, form a benzo ring, R₄ is additionally —(CH₂)_(p)—COR₁₅ or —CH₂)_(q)OH or, if R₃, R₅ and R₆ are hydrogen, R₄ is additionally a radical of the formula III

in which R₁ is defined as indicated above for n=1, R₆ is hydrogen or a radical of the formula IV

where R₄ is not a radical of the formula III and R₁ is defined as indicated above for n=1, R₇, R₈, R₉, R₁₀ and R₁₁ independently of one another are hydrogen, halogen, hydroxyl, C₁-C₂₅alkyl, C₂-C₂₅alkyl interrupted by oxygen, sulfur or

C₁-C₂₅alkoxy, C₂-C₂₅alkoxy interrupted by oxygen, sulfur or

C₁-C₂₅alkylthio, C₃-C₂₅alkenyl, C₃-C₂₅alkenyloxy, C₃-C₂₅alkynyl, C₃-C₂₅alkynyloxy, C₇-C₉phenylalkyl, C₇-C₉unsubstituted or C₁-C₄alkyl-substituted phenyl; unsubstituted or C₁-C₄alkyl-substituted phenoxy; unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkyl; unsubstituted or C₁-C₄alkyl-substituted C₅-C₈cycloalkoxy; C₁-C₄alkylamino, di(C₁-C₄alkyl)amino, C₁-C₂₅alkanoyl, C₃-C ₂₅alkanoyl interrupted by oxygen, sulfur or

C₁-C₂₅alkanoyloxy, C₃-C₂₅alkanoyloxy interrupted by oxygen, sulfur or

C₁-C₂₅alkanoylamino, C₃-C₂₅alkenoyl, C₃-C₂₅alkenoyl interrupted by oxygen, sulfur or

C₃-C₂₅alkenoyloxy, C₃-C₂₅alkenoyloxy interrupted by oxygen, sulfur or

C₆-C₉cycloalkylcarbonyl, C₆-C₉cycloalkylcarbonyloxy, benzoyl or C₁-C₁₂alkyl-substituted benzoyl; benzoyloxy or C₁-C₁₂alkyl-substituted benzoyloxy;

or else, in formula II, the radicals R₇ and R₈ or the radicals R₈ and R₁₁, together with the carbon atoms to which they are attached, form a benzo ring, R₁₂ and R₁₃ independently of one another are unsubstituted or C₁-C₄alkyl-substituted phenylene or naphthylene, R₁₄ is hydrogen or C₁-C₈alkyl, R₁₅ is hydroxyl,

R₁₆ and R₁₇ independently of one another are hydrogen, CF₃, C₁-C₁₂alkyl or phenyl, or R₁₆ and R₁₇, together with the C atom to which they are attached, form a C₅-C₈cycloalkylidene ring which is unsubstituted or substituted from 1 to 3 times by C₁-C₄alkyl; R₁₈ and R₁₉ independently of one another are hydrogen, C₁-C₄alkyl or phenyl, R₂₀ is hydrogen or C₁-C₄alkyl, R₂₁ is hydrogen, unsubstituted or C₁-C₄alkyl-substituted phenyl; C₁-C₂₅alkyl, C₂-C₂₅alkyl interrupted by oxygen, sulfur or

C₇-C₉phenylalkyl which is unsubstituted or substituted on the phenyl radical from 1 to 3 times by C₁-C₄alkyl; C₇-C₂₅phenylalkyl which is unsubstituted or substituted on the phenyl radical from 1 to 3 times by C₁-C₄alkyl and interrupted by oxygen, sulfur or

or else the radicals R₂₀ and R₂₁, together with the carbon atoms to which they are attached, form a C₅-C₁₂cycloalkylene ring which is unsubstituted or substituted from 1 to 3 times by C₁-C₄alkyl; R₂₂ is hydrogen or C₁-C₄alkyl, R₂₃ is hydrogen, C₁-C₂₅alkanoyl, C₃-C₂₅alkenoyl, C₃-C₂₅alkanoyl interrupted by oxygen, sulfur or

C₂-C₂₅alkanoyl substituted by a di(C₁-C₆alkyl)phosphonate group; C₆-C₉cycloalkylcarbonyl, thenoyl, furoyl, benzoyl or C₁-C₁₂alkyl-substituted benzoyl;

R₂₄ and R₂₅ independently of one another are hydrogen or C₁-C₁₈alkyl, R₂₆ is hydrogen or C₁-C₈alkyl, R₂₇ is a direct bond, C₁-C₁₈alkylene, C₂-C₁₈alkylene interrupted by oxygen, sulfur or

C₂-C₁₈alkenylene, C₂-C₂₀alkylidene, C₇-C₂₀phenylalkylidene, C₅-C₈cycloalkylene, C₇-C₈bicycloalkylene, unsubstituted or C₁-C₄alkyl-substituted phenylene, or

R₂₈ is hydroxyl,

R₂₉ is oxygen, —NH— or

R₃₀ is C₁-C₁₈alkyl or phenyl, R₃₁ is hydrogen or C₁-C₁₈alkyl, M is an r-valent metal cation, X is a direct bond, oxygen, sulfur or —NR₃₁—, n is 1 or 2, p is 0, 1 or 2, q is 1, 2, 3, 4, 5 or 6, r is 1, 2 or 3, and s is 0, 1 or
 2. 11. A composition according to claim 10 wherein the 3-arylbenzofuranones are of formula I wherein n=1, R₁ is phenyl which is unsubstituted or substituted in para-position by C₁-C₁₈alkylthio or di(C₁-C₄alkyl)amino; mono- to penta-substituted alkyphenyl containing together a total of at most 18 carbon atoms in the 1 to 5 alkyl substituents; naphthyl, biphenyl, terphenyl, phenanthryl, anthryl, fluorenyl, carbazolyl, thienyl, pyrrolyl, phenothizinyl or 5,6,7,8-tetrahydronaphthyl, each of which is unsubstituted or substituted by C₁-C₄alkyl, C₁-C₄alkoxy, C₁-C₄alkylthio, hydroxy or amino.
 12. A composition according to claim 10 wherein the 3-arylbenzofuranones are of formula I wherein n is 2, R₁ is —R₁₂—X—R₁₃—, R₁₂ and R₁₃ are phenylene, X is oxygen or —NR ₃₁—, and R₃₁ is C₁-C₄alkyl.
 13. A composition according to claim 10 wherein the 3-arylbenzofuranones are selected from the group consisting of 3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-tert-butyl-benzofuran-2-one; 5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]benzofuran-2-one; 3,3′-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one]; 5,7-di-tert -butyl-3-(4-ethoxyphenyl) benzofuran-2-one; 3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2-one; 3-(3,5-dimethyl-4-pivaloyloxy-phenyl)-5,7-di-tert-butyl-benzofuran-2-one; 5,7-di-tert-butyl-3-phenylbenzofuran-2-one; 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)-benzofuran-2-one and 5,7-di-tert-butyl-3-(2,3-dimethylphenyl)benzofuran-2-one.
 14. A composition according to claim 9 where the hindered phenolic antioxidants are selected from the group consisting of butylated hydroxytoluene, butylated hydroxyanisole, tocopherol, benzylphosphonates, esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols and esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols.
 15. A composition according to claim 1 comprising one or more hindered amine light stabilizers and one or more hindered phenolic antioxidants.
 16. A composition according to claim 15 where the hindered amine light stabilizers contain at least one moiety of formula

where G₁, G₂, G₃, G₄ and G₅ are independently alkyl of 1 to 8 carbon atoms or G₁ and G₂ or G₃ and G₄ together are pentamethylene.
 17. A composition according to claim 15 where the hindered amine stabilizers are selected from the group consisting of 1) 1-cyclohexyloxy-2,2,6,6-tetramethyl-4-octadecylaminopiperidine, 2) bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 3) bis(1-acetoxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 4) bis(1,2,2,6,6-pentamethyl-4-yl) sebacate, 5) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 6) bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate; 7) bis(1-acyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 8) bis(1,2,2,6,6-pentamethyl-4-piperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate 9) 2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-6-(2-hydroxy-ethylamino-s-triazine, 10) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) adipate, 11) 2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin-4-yl)butylamino]-6-chloro-s-triazine, 12) 1-(2-hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpiperidine, 13) 1-(2-hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiperidine, 14) 1-(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetramethylpiperidine, 15) bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 16) bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl) adipate, 17) 2,4-bis{N-[1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N -butyl-amino}-6-(2-hydroxyethylamino)-s-triazine, 18) 4-benzoyl-2,2,6,6-tetramethylpiperidine, 19) di-(1,2,2,6,6-pentamethylpiperidin-4-yl) p-methoxybenzylidenemalonate, 20) 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 21) bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, 22) 1,2,2,6,6-pentamethyl-4-aminopiperidine, 23) 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane, 24) tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate, 25) tris(2-hydroxy-3-(amino-(2,2,6,6-tetramethylpiperidin-4-yl)propyl) nitrilotriacetate, 26) tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 27) tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 28) 1,1′-(1,2-ethanedlyl)-bis(3,3,5,5-tetramethylpiperazinone), 29) 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione, 30) 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione, 31) 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione, 32) 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione, 33) N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine, 34) the reaction product of 2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin-4-yl)butylamino]-6-chloro -s-triazine with N,N′-bis(3-aminopropyl)ethylenediamine), 35) the condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, 36) linear or cyclic condensates of N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine, 37) linear or cyclic condensates of N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, 38) linear or cyclic condensates of N,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, 39) linear or cyclic condensates of N,N′-bis-(1,2,2,6,6-pentamethyl-4-piperidyl)-hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, 40) the condensate of 2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, 41) the condensate of 2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine and 1,2-bis-(3-aminopropylamino)ethane, 42) a reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro [4,5]decane and epichlorohydrin, 43) poly[methyl, (3-oxy-(2,2,6,6-tetramethylpiperidin-4-yl)propyl)] siloxane, CAS#182635-99-0, 44) reaction product of maleic acid anhydride-C₁₈-C₂₂-α-olefin-copolymer with 2,2,6,6-tetramethyl-4-aminopiperidine, 45) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis(amino-2, 2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, 46) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis(amino-1,2,2,6,6-pentaamethylpiperidine) and 2,4-dichloro-6-[(1,2,2,6,6-pentaamethyl-piperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, 47) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis(amino-1-propoxy-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1-propoxy-2,2,6,6-tetra-methylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, 48) the oligomeric compound which is the condensation product of 4,4′-hexamethylene-bis (amino-1-acyloxy-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1-acyloxy-2,2,6,6-tetra-methylpiperidin -4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine and 49) product obtained by reacting a product, obtained by reacting 1,2-bis(3-amino-propylamino) ethane with cyanuric chloride, with (2,2,6,6-tetramethylpiperidin-4-yl)butylamine.
 18. A composition according to claim 15 where the hindered amine is an N—H, N-methyl, N-methoxy, N-propoxy, N-octyloxy, N-cyclohexyloxy, N-acyloxy or an N-(2-hydroxy-2-methyl-propoxy) substituted amine.
 19. A composition according to claim 15 where the hindered phenolic antioxidants are selected from the group consisting of butylated hydroxytoluene, butylated hydroxyanisole, tocopherol, benzylphosphonates, esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols and esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols.
 20. A process for the stabilization of a biodiesel fuel against the deleterious effects of heat, light and oxygen, which process comprises incorporating into a biodiesel fuel an effective stabilizing amount of one or more additives selected from the group consisting of the 3-arylbenzofuranone stabilizers and the hindered amine light stabilizers and optionally, one or more additives selected from the group consisting of the hindered phenolic antioxidants. 